Research On Traffic Bottleneck Identification Of Urban Road Network

One of the urban problems currently appearing in the cities is traffic congestion, which makes a serious influence on people’s production and living life, and disrupts the traffic’s order. While traffic bottleneck is the source of the traffic congestion. So taking the traffic bottleneck as the key point and researching traffic congestion make a good sense in theoretical and practical fields. In this paper, the traffic bottleneck of the road network is regarded as the research object. In addition, the identification of traffic bottlenecks is researched carefully based on the present relevant studying outcomes in domestic and abroad countries.Firstly, the reasons of traffic congestion are analyzed with economical theories and the conclusion is that the traffic jams occur necessarily due to the traffic supply and demand contradiction. Moreover, the relation between traffic congestion and traffic bottleneck is discussed. As a result, the basic cause of congestion is traffic jams from the perspective of the structure of road network and traffic demand. The further research is carried out with the above analysis. Additionally, the concept of traffic bottleneck and the classification of it are defined according to different standards. Also, both the static and dynamic factors influencing the bottleneck are described which establishes the basis of its following identification.Secondly, a simple and practical method—service level is used to identify the fixed traffic bottleneck. On the basis of the capacity of sections and intersections in the road network, the saturation of sections and intersections is obtained in combination with the investigation of detailed traffic volume data. Then the traffic bottleneck is identified with the corresponding bottleneck recognition criteria. Taking Chengguan district in Lanzhou as an example, a road network graph is worked out according the city’s map. Meanwhile, the service level of each section and intersection is calculated, marking them with different colors. While the service level reaches D(marked in red), the section or intersection is named as a traffic bottleneck. Hereby, all the traffic bottlenecks in Chengguan district are found one by one. Therefore the distribution of section and intersection in differential service level and the bottlenecks scale are received.Thirdly, the maximal flow-minimal cut method is used to identify dynamic traffic bottleneck. The mathematic model of bottleneck recognition based on maximum flow and the capability matching model of sections and intersections are established. Besides, the basic process of dynamic bottleneck identification and the order principle of bottleneck are proposed. Considering these methods’ application, the identification method of dynamic line bottleneck is put forwarded by computer. At the same time, the database of road network and the data process procedure are created. With Ford-Fulkerson labeling method, the dynamic bottleneck identification algorithm is implemented. Still choosing Chengguan as background, the dynamic line bottleneck is identified from the perspective of the time dimension combining with investigation data. Meanwhile, the traffic line bottleneck is sorted according to the sequencing of bottleneck identification, and is marked in different line thickness in the graph. The thicker the line is, the higher is the rank of bottlenecks and the more seriously the impact on traffic congestion is.Finally, combined with the results of traffic bottleneck identification, the deeper relationship between traffic demand and traffic bottlenecks is analyzed, following which the strategies of improving traffic bottleneck are put forward to release the traffic congestion. Through these analysis of the traffic bottleneck, its application methods and conclusions can provide some basic theoretical reference for traffic congestion for further research in the future, it can also provide suggestion for the research and practice related to the transportation planning and management in the future in Lanzhou city.